#include <limits.h>
#include <stddef.h>
#include <string.h>
#include "tlsf.h"

#define likely(x)      __builtin_expect(!!(x), 1)
#define unlikely(x)    __builtin_expect(!!(x), 0)

static inline int tlsf_ffs(unsigned int word)
{
  return __builtin_ffs(word) - 1;
}

static inline int tlsf_fls(unsigned int word)
{
  const int bit = word ? 32 - __builtin_clz(word) : 0;
  return bit - 1;
}

// 32 bits mode
#define tlsf_fls_sizet(w) tlsf_fls(w)


/*
** Constants.
*/

/* Public constants: may be modified. */
enum tlsf_public
  {
    /* log2 of number of linear subdivisions of block sizes. */
#ifdef MAX_LOG2_SLI
    SL_INDEX_COUNT_LOG2 = MAX_LOG2_SLI,
#else
    SL_INDEX_COUNT_LOG2 = 5,
#endif
  };

/* Private constants: do not modify. */
enum tlsf_private
  {
#if defined (TLSF_64BIT)
    /* All allocation sizes and addresses are aligned to 8 bytes. */
    ALIGN_SIZE_LOG2 = 3,
#else
    /* All allocation sizes and addresses are aligned to 4 bytes. */
    ALIGN_SIZE_LOG2 = 2,
#endif
    ALIGN_SIZE = (1 << ALIGN_SIZE_LOG2),

    /*
    ** We support allocations of sizes up to (1 << FL_INDEX_MAX) bits.
    ** However, because we linearly subdivide the second-level lists, and
    ** our minimum size granularity is 4 bytes, it doesn't make sense to
    ** create first-level lists for sizes smaller than SL_INDEX_COUNT * 4,
    ** or (1 << (SL_INDEX_COUNT_LOG2 + 2)) bytes, as there we will be
    ** trying to split size ranges into more slots than we have available.
    ** Instead, we calculate the minimum threshold size, and place all
    ** blocks below that size into the 0th first-level list.
    */

#if defined (TLSF_64BIT)
    /*
    ** TODO: We can increase this to support larger sizes, at the expense
    ** of more overhead in the TLSF structure.
    */
    FL_INDEX_MAX = 32,
#elif defined  MAX_FLI
    FL_INDEX_MAX = MAX_FLI,
#else
    FL_INDEX_MAX = 30,
#endif
    SL_INDEX_COUNT = (1 << SL_INDEX_COUNT_LOG2),
    FL_INDEX_SHIFT = (SL_INDEX_COUNT_LOG2 + ALIGN_SIZE_LOG2),
    FL_INDEX_COUNT = (FL_INDEX_MAX - FL_INDEX_SHIFT + 1),

    SMALL_BLOCK_SIZE = (1 << FL_INDEX_SHIFT),
  };


static error_cb_t error_cb =NULL;
#define tlsf_error(msg) {			\
    if (unlikely (error_cb != NULL))		\
      error_cb(msg);				\
  }


/*
** Cast and min/max macros.
*/

#define tlsf_cast(t, exp)	((t) (exp))
#define tlsf_min(a, b)		((a) < (b) ? (a) : (b))
#define tlsf_max(a, b)		((a) > (b) ? (a) : (b))

/*
** Set assert macro, if it has not been provided by the user.
*/
#if !defined (tlsf_assert)
//#define tlsf_assert(x) assert(x)
#define tlsf_assert(x) {if (!(x)) tlsf_error(#x);}
#endif

/*
** Static assertion mechanism.
*/

#define _tlsf_glue2(x, y) x ## y
#define _tlsf_glue(x, y) _tlsf_glue2(x, y)
#define tlsf_static_assert(exp)						\
  typedef char _tlsf_glue(static_assert, __LINE__) [(exp) ? 1 : -1]

/* This code has been tested on 32- and 64-bit (LP/LLP) architectures. */
tlsf_static_assert(sizeof(int) * CHAR_BIT == 32);
tlsf_static_assert(sizeof(size_t) * CHAR_BIT >= 32);
tlsf_static_assert(sizeof(size_t) * CHAR_BIT <= 64);

/* SL_INDEX_COUNT must be <= number of bits in sl_bitmap's storage type. */
tlsf_static_assert(sizeof(unsigned int) * CHAR_BIT >= SL_INDEX_COUNT);

/* Ensure we've properly tuned our sizes. */
tlsf_static_assert(ALIGN_SIZE == SMALL_BLOCK_SIZE / SL_INDEX_COUNT);

/*
** Data structures and associated constants.
*/

/*
** Block header structure.
**
** There are several implementation subtleties involved:
** - The prev_phys_block field is only valid if the previous block is free.
** - The prev_phys_block field is actually stored at the end of the
**   previous block. It appears at the beginning of this structure only to
**   simplify the implementation.
** - The next_free / prev_free fields are only valid if the block is free.
*/
typedef struct block_header_t
{
  /* Points to the previous physical block. */
  struct block_header_t* prev_phys_block;

  /* The size of this block, excluding the block header. */
  size_t size;

  /* Next and previous free blocks. */
  struct block_header_t* next_free;
  struct block_header_t* prev_free;
} block_header_t;

/*
** Since block sizes are always at least a multiple of 4, the two least
** significant bits of the size field are used to store the block status:
** - bit 0: whether block is busy or free
** - bit 1: whether previous block is busy or free
*/
static const size_t block_header_free_bit = 1 << 0;
static const size_t block_header_prev_free_bit = 1 << 1;

/*
** The size of the block header exposed to used blocks is the size field.
** The prev_phys_block field is stored *inside* the previous free block.
*/
static const size_t block_header_overhead = sizeof(size_t);

/* User data starts directly after the size field in a used block. */
static const size_t block_start_offset = offsetof(block_header_t, size) + sizeof(size_t);

/*
 ** A free block must be large enough to store its header minus the size of
 ** the prev_phys_block field, and no larger than the number of addressable
 ** bits for FL_INDEX.
 */
static const size_t block_size_min = sizeof(block_header_t) - sizeof(block_header_t*);
static const size_t block_size_max = tlsf_cast(size_t, 1) << FL_INDEX_MAX;


/* The TLSF control structure. */
typedef struct control_t
{
  /* Empty lists point at this block to indicate they are free. */
  block_header_t block_null;

  /* Bitmaps for free lists. */
  unsigned int fl_bitmap;
  unsigned int sl_bitmap[FL_INDEX_COUNT];

  /* Head of free lists. */
  block_header_t* blocks[FL_INDEX_COUNT][SL_INDEX_COUNT];
} control_t;

/* A type used for casting when doing pointer arithmetic. */
typedef ptrdiff_t tlsfptr_t;

/*
** block_header_t member functions.
*/

static size_t block_size(const block_header_t* block)
{
  return block->size & ~(block_header_free_bit | block_header_prev_free_bit);
}

static void block_set_size(block_header_t* block, size_t size)
{
  const size_t oldsize = block->size;
  block->size = size | (oldsize & (block_header_free_bit | block_header_prev_free_bit));
}

static int block_is_last(const block_header_t* block)
{
  return 0 == block_size(block);
}

static int block_is_free(const block_header_t* block)
{
  return tlsf_cast(int, block->size & block_header_free_bit);
}

static void block_set_free(block_header_t* block)
{
  block->size |= block_header_free_bit;
}

static void block_set_used(block_header_t* block)
{
  block->size &= ~block_header_free_bit;
}

static int block_is_prev_free(const block_header_t* block)
{
  return tlsf_cast(int, block->size & block_header_prev_free_bit);
}

static void block_set_prev_free(block_header_t* block)
{
  block->size |= block_header_prev_free_bit;
}

static void block_set_prev_used(block_header_t* block)
{
  block->size &= ~block_header_prev_free_bit;
}

static block_header_t* block_from_ptr(const void* ptr)
{
  return tlsf_cast(block_header_t*,
		   tlsf_cast(unsigned char*, ptr) - block_start_offset);
}

static void* block_to_ptr(const block_header_t* block)
{
  return tlsf_cast(void*,
		   tlsf_cast(unsigned char*, block) + block_start_offset);
}

/* Return location of next block after block of given size. */
static block_header_t* offset_to_block(const void* ptr, size_t size)
{
  return tlsf_cast(block_header_t*, tlsf_cast(tlsfptr_t, ptr) + size);
}

/* Return location of previous block. */
static block_header_t* block_prev(const block_header_t* block)
{
  return block->prev_phys_block;
}

/* Return location of next existing block. */
static block_header_t* block_next(const block_header_t* block)
{
  block_header_t* next = offset_to_block(block_to_ptr(block),
					 block_size(block) - block_header_overhead);
  tlsf_assert(!block_is_last(block));
  return next;
}

/* Link a new block with its physical neighbor, return the neighbor. */
static block_header_t* block_link_next(block_header_t* block)
{
  block_header_t* next = block_next(block);
  next->prev_phys_block = block;
  return next;
}

static void block_mark_as_free(block_header_t* block)
{
  /* Link the block to the next block, first. */
  block_header_t* next = block_link_next(block);
  block_set_prev_free(next);
  block_set_free(block);
}

static void block_mark_as_used(block_header_t* block)
{
  block_header_t* next = block_next(block);
  block_set_prev_used(next);
  block_set_used(block);
}

static size_t align_up(size_t x, size_t align)
{
  tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
  return (x + (align - 1)) & ~(align - 1);
}

static size_t align_down(size_t x, size_t align)
{
  tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
  return x - (x & (align - 1));
}

static void* align_ptr(const void* ptr, size_t align)
{
  const tlsfptr_t aligned =
    (tlsf_cast(tlsfptr_t, ptr) + (align - 1)) & ~(align - 1);
  tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");
  return tlsf_cast(void*, aligned);
}

/*
** Adjust an allocation size to be aligned to word size, and no smaller
** than internal minimum.
*/
static size_t adjust_request_size(size_t size, size_t align)
{
  size_t adjust = 0;
  if (size && size < block_size_max)
    {
      const size_t aligned = align_up(size, align);
      adjust = tlsf_max(aligned, block_size_min);
    }
  return adjust;
}

/*
** TLSF utility functions. In most cases, these are direct translations of
** the documentation found in the white paper.
*/

static void mapping_insert(size_t size, int* fli, int* sli)
{
  int fl, sl;
  if (size < SMALL_BLOCK_SIZE)
    {
      /* Store small blocks in first list. */
      fl = 0;
      sl = tlsf_cast(int, size) / (SMALL_BLOCK_SIZE / SL_INDEX_COUNT);
    }
  else
    {
      fl = tlsf_fls_sizet(size);
      sl = tlsf_cast(int, size >> (fl - SL_INDEX_COUNT_LOG2)) ^ (1 << SL_INDEX_COUNT_LOG2);
      fl -= (FL_INDEX_SHIFT - 1);
    }
  *fli = fl;
  *sli = sl;
}

/* This version rounds up to the next block size (for allocations) */
static void mapping_search(size_t size, int* fli, int* sli)
{
  if (size >= (1 << SL_INDEX_COUNT_LOG2))
    {
      const size_t round = (1 << (tlsf_fls_sizet(size) - SL_INDEX_COUNT_LOG2)) - 1;
      size += round;
    }
  mapping_insert(size, fli, sli);
}

static block_header_t* search_suitable_block(control_t* control, int* fli, int* sli)
{
  int fl = *fli;
  int sl = *sli;

  /*
  ** First, search for a block in the list associated with the given
  ** fl/sl index.
  */
  unsigned int sl_map = control->sl_bitmap[fl] & (~0U << sl);
  if (!sl_map)
    {
      /* No block exists. Search in the next largest first-level list. */
      const unsigned int fl_map = control->fl_bitmap & (~0U << (fl + 1));
      if (!fl_map)
	{
	  /* No free blocks available, memory has been exhausted. */
	  return 0;
	}

      fl = tlsf_ffs(fl_map);
      *fli = fl;
      sl_map = control->sl_bitmap[fl];
    }
  tlsf_assert(sl_map && "internal error - second level bitmap is null");
  sl = tlsf_ffs(sl_map);
  *sli = sl;

  /* Return the first block in the free list. */
  return control->blocks[fl][sl];
}

/* Remove a free block from the free list.*/
static void remove_free_block(control_t* control, block_header_t* block, int fl, int sl)
{
  block_header_t* prev = block->prev_free;
  block_header_t* next = block->next_free;
  tlsf_assert(prev && "prev_free field can not be null");
  tlsf_assert(next && "next_free field can not be null");
  next->prev_free = prev;
  prev->next_free = next;

  /* If this block is the head of the free list, set new head. */
  if (control->blocks[fl][sl] == block)
    {
      control->blocks[fl][sl] = next;

      /* If the new head is null, clear the bitmap. */
      if (next == &control->block_null)
	{
	  control->sl_bitmap[fl] &= ~(1 << sl);

	  /* If the second bitmap is now empty, clear the fl bitmap. */
	  if (!control->sl_bitmap[fl])
	    {
	      control->fl_bitmap &= ~(1 << fl);
	    }
	}
    }
}

/* Insert a free block into the free block list. */
static void insert_free_block(control_t* control, block_header_t* block, int fl, int sl)
{
  block_header_t* current = control->blocks[fl][sl];
  tlsf_assert(current && "free list cannot have a null entry");
  tlsf_assert(block && "cannot insert a null entry into the free list");
  block->next_free = current;
  block->prev_free = &control->block_null;
  current->prev_free = block;

  tlsf_assert(block_to_ptr(block) == align_ptr(block_to_ptr(block), ALIGN_SIZE)
	      && "block not aligned properly");
  /*
  ** Insert the new block at the head of the list, and mark the first-
  ** and second-level bitmaps appropriately.
  */
  control->blocks[fl][sl] = block;
  control->fl_bitmap |= (1 << fl);
  control->sl_bitmap[fl] |= (1 << sl);
}

/* Remove a given block from the free list. */
static void block_remove(control_t* control, block_header_t* block)
{
  int fl, sl;
  mapping_insert(block_size(block), &fl, &sl);
  remove_free_block(control, block, fl, sl);
}

/* Insert a given block into the free list. */
static void block_insert(control_t* control, block_header_t* block)
{
  int fl, sl;
  mapping_insert(block_size(block), &fl, &sl);
  insert_free_block(control, block, fl, sl);
}

static int block_can_split(block_header_t* block, size_t size)
{
  return block_size(block) >= sizeof(block_header_t) + size;
}

/* Split a block into two, the second of which is free. */
static block_header_t* block_split(block_header_t* block, size_t size)
{
  /* Calculate the amount of space left in the remaining block. */
  block_header_t* remaining =
    offset_to_block(block_to_ptr(block), size - block_header_overhead);

  const size_t remain_size = block_size(block) - (size + block_header_overhead);

  tlsf_assert(block_to_ptr(remaining) == align_ptr(block_to_ptr(remaining), ALIGN_SIZE)
	      && "remaining block not aligned properly");

  tlsf_assert(block_size(block) == remain_size + size + block_header_overhead);
  block_set_size(remaining, remain_size);
  tlsf_assert(block_size(remaining) >= block_size_min && "block split with invalid size");

  block_set_size(block, size);
  block_mark_as_free(remaining);

  return remaining;
}

/* Absorb a free block's storage into an adjacent previous free block. */
static block_header_t* block_absorb(block_header_t* prev, block_header_t* block)
{
  tlsf_assert(!block_is_last(prev) && "previous block can't be last!");
  /* Note: Leaves flags untouched. */
  prev->size += block_size(block) + block_header_overhead;
  block_link_next(prev);
  return prev;
}

/* Merge a just-freed block with an adjacent previous free block. */
static block_header_t* block_merge_prev(control_t* control, block_header_t* block)
{
  if (block_is_prev_free(block))
    {
      block_header_t* prev = block_prev(block);
      tlsf_assert(prev && "prev physical block can't be null");
      tlsf_assert(block_is_free(prev) && "prev block is not free though marked as such");
      block_remove(control, prev);
      block = block_absorb(prev, block);
    }

  return block;
}

/* Merge a just-freed block with an adjacent free block. */
static block_header_t* block_merge_next(control_t* control, block_header_t* block)
{
  block_header_t* next = block_next(block);
  tlsf_assert(next && "next physical block can't be null");

  if (block_is_free(next))
    {
      tlsf_assert(!block_is_last(block) && "previous block can't be last!");
      block_remove(control, next);
      block = block_absorb(block, next);
    }

  return block;
}

/* Trim any trailing block space off the end of a block, return to pool. */
static void block_trim_free(control_t* control, block_header_t* block, size_t size)
{
  tlsf_assert(block_is_free(block) && "block must be free");
  if (block_can_split(block, size))
    {
      block_header_t* remaining_block = block_split(block, size);
      block_link_next(block);
      block_set_prev_free(remaining_block);
      block_insert(control, remaining_block);
    }
}

/* Trim any trailing block space off the end of a used block, return to pool. */
static void block_trim_used(control_t* control, block_header_t* block, size_t size)
{
  tlsf_assert(!block_is_free(block) && "block must be used");
  if (block_can_split(block, size))
    {
      /* If the next block is free, we must coalesce. */
      block_header_t* remaining_block = block_split(block, size);
      block_set_prev_used(remaining_block);

      remaining_block = block_merge_next(control, remaining_block);
      block_insert(control, remaining_block);
    }
}

static block_header_t* block_trim_free_leading(control_t* control, block_header_t* block, size_t size)
{
  block_header_t* remaining_block = block;
  if (block_can_split(block, size))
    {
      /* We want the 2nd block. */
      remaining_block = block_split(block, size - block_header_overhead);
      block_set_prev_free(remaining_block);

      block_link_next(block);
      block_insert(control, block);
    }

  return remaining_block;
}

static block_header_t* block_locate_free(control_t* control, size_t size)
{
  int fl = 0, sl = 0;
  block_header_t* block = 0;

  if (size)
    {
      mapping_search(size, &fl, &sl);
      block = search_suitable_block(control, &fl, &sl);
    }

  if (block)
    {
      tlsf_assert(block_size(block) >= size);
      remove_free_block(control, block, fl, sl);
    }

  return block;
}

static void* block_prepare_used(control_t* control, block_header_t* block, size_t size)
{
  void* p = 0;
  if (block)
    {
      block_trim_free(control, block, size);
      block_mark_as_used(block);
      p = block_to_ptr(block);
    }
  return p;
}

/* Clear structure and point all empty lists at the null block. */
static void control_construct(control_t* control)
{
  int i, j;

  control->block_null.next_free = &control->block_null;
  control->block_null.prev_free = &control->block_null;

  control->fl_bitmap = 0;
  for (i = 0; i < FL_INDEX_COUNT; ++i)
    {
      control->sl_bitmap[i] = 0;
      for (j = 0; j < SL_INDEX_COUNT; ++j)
	{
	  control->blocks[i][j] = &control->block_null;
	}
    }
}

/*
** Debugging utilities.
*/


typedef struct integrity_t
{
  int prev_status;
  int status;
} integrity_t;

#define tlsf_insist(x) { tlsf_assert(x); if (!(x)) { status--; } }

static void integrity_walker(void* ptr, size_t size, int used, void* user)
{
  (void) used;
  block_header_t* block = block_from_ptr(ptr);
  integrity_t* integ = tlsf_cast(integrity_t*, user);
  const int this_prev_status = block_is_prev_free(block) ? 1 : 0;
  const int this_status = block_is_free(block) ? 1 : 0;
  const size_t this_block_size = block_size(block);

  int status = 0;
  tlsf_insist(integ->prev_status == this_prev_status && "prev status incorrect");
  tlsf_insist(size == this_block_size && "block size incorrect");

  integ->prev_status = this_status;
  integ->status += status;
}

int tlsf_check(tlsf_t tlsf)
{
  int i, j;

  control_t* control = tlsf_cast(control_t*, tlsf);
  int status = 0;

  /* Check that the free lists and bitmaps are accurate. */
  for (i = 0; i < FL_INDEX_COUNT; ++i)
    {
      for (j = 0; j < SL_INDEX_COUNT; ++j)
	{
	  const int fl_map = control->fl_bitmap & (1 << i);
	  const int sl_list = control->sl_bitmap[i];
	  const int sl_map = sl_list & (1 << j);
	  const block_header_t* block = control->blocks[i][j];

	  /* Check that first- and second-level lists agree. */
	  if (!fl_map)
	    {
	      tlsf_insist(!sl_map && "second-level map must be null");
	    }

	  if (!sl_map)
	    {
	      tlsf_insist(block == &control->block_null && "block list must be null");
	      continue;
	    }

	  /* Check that there is at least one free block. */
	  tlsf_insist(sl_list && "no free blocks in second-level map");
	  tlsf_insist(block != &control->block_null && "block should not be null");

	  while (block != &control->block_null)
	    {
	      int fli, sli;
	      tlsf_insist(block_is_free(block) && "block should be free");
	      tlsf_insist(!block_is_prev_free(block) && "blocks should have coalesced");
	      tlsf_insist(!block_is_free(block_next(block)) && "blocks should have coalesced");
	      tlsf_insist(block_is_prev_free(block_next(block)) && "block should be free");
	      tlsf_insist(block_size(block) >= block_size_min && "block not minimum size");

	      mapping_insert(block_size(block), &fli, &sli);
	      tlsf_insist(fli == i && sli == j && "block size indexed in wrong list");
	      block = block->next_free;
	    }
	}
    }

  return status;
}

#undef tlsf_insist


void tlsf_walk_pool(pool_t pool, tlsf_walker walker, void* user)
{
  tlsf_walker pool_walker = walker ;
  block_header_t* block =
    offset_to_block(pool, -(int)block_header_overhead);

  while (block && !block_is_last(block))
    {
      pool_walker(
		  block_to_ptr(block),
		  block_size(block),
		  !block_is_free(block),
		  user);
      block = block_next(block);
    }
}

size_t tlsf_block_size(void* ptr)
{
  size_t size = 0;
  if (ptr)
    {
      const block_header_t* block = block_from_ptr(ptr);
      size = block_size(block);
    }
  return size;
}

int tlsf_check_pool(pool_t pool)
{
  /* Check that the blocks are physically correct. */
  integrity_t integ = { 0, 0 };
  tlsf_walk_pool(pool, integrity_walker, &integ);

  return integ.status;
}

/*
** Size of the TLSF structures in a given memory block passed to
** tlsf_create, equal to the size of a control_t
*/
size_t tlsf_size(void)
{
  return sizeof(control_t);
}

size_t tlsf_align_size(void)
{
  return ALIGN_SIZE;
}

size_t tlsf_block_size_min(void)
{
  return block_size_min;
}

size_t tlsf_block_size_max(void)
{
  return block_size_max;
}

/*
** Overhead of the TLSF structures in a given memory block passes to
** tlsf_add_pool, equal to the overhead of a free block and the
** sentinel block.
*/
size_t tlsf_pool_overhead(void)
{
  return 2 * block_header_overhead;
}

size_t tlsf_alloc_overhead(void)
{
  return block_header_overhead;
}

pool_t tlsf_add_pool(tlsf_t tlsf, void* mem, size_t bytes)
{
  block_header_t* block;
  block_header_t* next;

  const size_t pool_overhead = tlsf_pool_overhead();
  const size_t pool_bytes = align_down(bytes - pool_overhead, ALIGN_SIZE);

  if (((ptrdiff_t)mem % ALIGN_SIZE) != 0)
    {
      tlsf_error("tlsf_add_pool: Memory must be aligned by ALIGN_SIZE bytes");
      return 0;
    }

  if (pool_bytes < block_size_min || pool_bytes > block_size_max)
    {
      tlsf_error("tlsf_add_pool: Memory size error, adjust MAX_FLI constant");
      return 0;
    }

  /*
  ** Create the main free block. Offset the start of the block slightly
  ** so that the prev_phys_block field falls outside of the pool -
  ** it will never be used.
  */
  block = offset_to_block(mem, -(tlsfptr_t)block_header_overhead);
  block_set_size(block, pool_bytes);
  block_set_free(block);
  block_set_prev_used(block);
  block_insert(tlsf_cast(control_t*, tlsf), block);

  /* Split the block to create a zero-size sentinel block. */
  next = block_link_next(block);
  block_set_size(next, 0);
  block_set_used(next);
  block_set_prev_free(next);

  return mem;
}

void tlsf_remove_pool(tlsf_t tlsf, pool_t pool)
{
  control_t* control = tlsf_cast(control_t*, tlsf);
  block_header_t* block = offset_to_block(pool, -(int)block_header_overhead);

  int fl = 0, sl = 0;

  tlsf_assert(block_is_free(block) && "block should be free");
  tlsf_assert(!block_is_free(block_next(block)) && "next block should not be free");
  tlsf_assert(block_size(block_next(block)) == 0 && "next block size should be zero");

  mapping_insert(block_size(block), &fl, &sl);
  remove_free_block(control, block, fl, sl);
}

/*
** TLSF main interface.
*/

#if defined TLSF_DEBUG && TLSF_DEBUG
int test_ffs_fls(void)
{
  /* Verify ffs/fls work properly. */
  int rv = 0;
  rv += (tlsf_ffs(0) == -1) ? 0 : 0x1;
  rv += (tlsf_fls(0) == -1) ? 0 : 0x2;
  rv += (tlsf_ffs(1) == 0) ? 0 : 0x4;
  rv += (tlsf_fls(1) == 0) ? 0 : 0x8;
  rv += (tlsf_ffs(0x80000000) == 31) ? 0 : 0x10;
  rv += (tlsf_ffs(0x80008000) == 15) ? 0 : 0x20;
  rv += (tlsf_fls(0x80000008) == 31) ? 0 : 0x40;
  rv += (tlsf_fls(0x7FFFFFFF) == 30) ? 0 : 0x80;

#if defined (TLSF_64BIT)
  rv += (tlsf_fls_sizet(0x80000000) == 31) ? 0 : 0x100;
  rv += (tlsf_fls_sizet(0x100000000) == 32) ? 0 : 0x200;
  rv += (tlsf_fls_sizet(0xffffffffffffffff) == 63) ? 0 : 0x400; 
#endif

  if (rv)
    {
      tlsf_error("tlsf_create: ffs/fls tests failed");
    }
  return rv;
}
#endif

tlsf_t tlsf_create(void* mem, error_cb_t _error_cb)
{
  error_cb = _error_cb;

#if defined TLSF_DEBUG && TLSF_DEBUG
  if (test_ffs_fls())
    {
      return 0;
    }
#endif

  if (((tlsfptr_t)mem % ALIGN_SIZE) != 0)
    {
      tlsf_error("tlsf_create: Memory must be aligned to ALIGN_SIZE bytes");
      return 0;
    }

  control_construct(tlsf_cast(control_t*, mem));

  return tlsf_cast(tlsf_t, mem);
}

tlsf_t tlsf_create_with_pool(void* mem, size_t bytes, error_cb_t _error_cb)
{
  tlsf_t tlsf = tlsf_create(mem, _error_cb);
  tlsf_add_pool(tlsf, (char*)mem + tlsf_size(), bytes - tlsf_size());
  return tlsf;
}

void tlsf_destroy(tlsf_t tlsf)
{
  /* Nothing to do. */
  (void)tlsf;
}

pool_t tlsf_get_pool(tlsf_t tlsf)
{
  return tlsf_cast(pool_t, (char*)tlsf + tlsf_size());
}

void* tlsf_malloc(tlsf_t tlsf, size_t size)
{
  control_t* control = tlsf_cast(control_t*, tlsf);
  const size_t adjust = adjust_request_size(size, ALIGN_SIZE);
  block_header_t* block = block_locate_free(control, adjust);
  return block_prepare_used(control, block, adjust);
}

void* tlsf_memalign(tlsf_t tlsf, size_t align, size_t size)
{
  control_t* control = tlsf_cast(control_t*, tlsf);
  const size_t adjust = adjust_request_size(size, ALIGN_SIZE);

  /*
  ** We must allocate an additional minimum block size bytes so that if
  ** our free block will leave an alignment gap which is smaller, we can
  ** trim a leading free block and release it back to the pool. We must
  ** do this because the previous physical block is in use, therefore
  ** the prev_phys_block field is not valid, and we can't simply adjust
  ** the size of that block.
  */
  const size_t gap_minimum = sizeof(block_header_t);
  const size_t size_with_gap = adjust_request_size(adjust + align + gap_minimum, align);

  /* If alignment is less than or equals base alignment, we're done. */
  const size_t aligned_size = (align <= ALIGN_SIZE) ? adjust : size_with_gap;

  block_header_t* block = block_locate_free(control, aligned_size);

  /* This can't be a static assert. */
  tlsf_assert(sizeof(block_header_t) == block_size_min + block_header_overhead);

  if (block)
    {
      void* ptr = block_to_ptr(block);
      void* aligned = align_ptr(ptr, align);
      size_t gap = tlsf_cast(size_t,
			     tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));

      /* If gap size is too small, offset to next aligned boundary. */
      if (gap && gap < gap_minimum)
	{
	  const size_t gap_remain = gap_minimum - gap;
	  const size_t offset = tlsf_max(gap_remain, align);
	  const void* next_aligned = tlsf_cast(void*,
					       tlsf_cast(tlsfptr_t, aligned) + offset);

	  aligned = align_ptr(next_aligned, align);
	  gap = tlsf_cast(size_t,
			  tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));
	}

      if (gap)
	{
	  tlsf_assert(gap >= gap_minimum && "gap size too small");
	  block = block_trim_free_leading(control, block, gap);
	}
    }

  return block_prepare_used(control, block, adjust);
}

void tlsf_free(tlsf_t tlsf, void* ptr)
{
  /* Don't attempt to free a NULL pointer. */
  if (ptr)
    {
      control_t* control = tlsf_cast(control_t*, tlsf);
      block_header_t* block = block_from_ptr(ptr);
      tlsf_assert(!block_is_free(block) && "block already marked as free");
      block_mark_as_free(block);
      block = block_merge_prev(control, block);
      block = block_merge_next(control, block);
      block_insert(control, block);
    }
}

/*
** The TLSF block information provides us with enough information to
** provide a reasonably intelligent implementation of realloc, growing or
** shrinking the currently allocated block as required.
**
** This routine handles the somewhat esoteric edge cases of realloc:
** - a non-zero size with a null pointer will behave like malloc
** - a zero size with a non-null pointer will behave like free
** - a request that cannot be satisfied will leave the original buffer
**   untouched
** - an extended buffer size will leave the newly-allocated area with
**   contents undefined
*/
void* tlsf_realloc(tlsf_t tlsf, void* ptr, size_t size)
{
  control_t* control = tlsf_cast(control_t*, tlsf);
  void* p = 0;

  /* Zero-size requests are treated as free. */
  if (ptr && size == 0)
    {
      tlsf_free(tlsf, ptr);
    }
  /* Requests with NULL pointers are treated as malloc. */
  else if (!ptr)
    {
      p = tlsf_malloc(tlsf, size);
    }
  else
    {
      block_header_t* block = block_from_ptr(ptr);
      block_header_t* next = block_next(block);

      const size_t cursize = block_size(block);
      const size_t combined = cursize + block_size(next) + block_header_overhead;
      const size_t adjust = adjust_request_size(size, ALIGN_SIZE);

      tlsf_assert(!block_is_free(block) && "block already marked as free");

      /*
      ** If the next block is used, or when combined with the current
      ** block, does not offer enough space, we must reallocate and copy.
      */
      if (adjust > cursize && (!block_is_free(next) || adjust > combined))
	{
	  p = tlsf_malloc(tlsf, size);
	  if (p)
	    {
	      const size_t minsize = tlsf_min(cursize, size);
	      memcpy(p, ptr, minsize);
	      tlsf_free(tlsf, ptr);
	    }
	}
      else
	{
	  /* Do we need to expand to the next block? */
	  if (adjust > cursize)
	    {
	      block_merge_next(control, block);
	      block_mark_as_used(block);
	    }

	  /* Trim the resulting block and return the original pointer. */
	  block_trim_used(control, block, adjust);
	  p = ptr;
	}
    }

  return p;
}
